Are you able to get out using Fedora? Meaning can you browse web pages.
If not, then try bridging the Vista LAN device with the Virtualbox host interface. Just highlight both interfaces, right click, and select "bridge" or "add to bridge". This will create a new interface, that will get ip via dhcp by default (can set static IP if you want). Then when you start Fedora via VBox, it should access your network through the host interface via the bridge.
Hope this helps.